Have conda check for EnvironmentNotWritableError BEFORE DOWNLOADING THE WHOLE THING

[Nicolás Casaballe]

I have just run conda update anaconda from the command line from Windows, and once again I have fallen for the EnvironmentNotWritableError: The current user does not have write permissions to the target environment.

I know it's my fault and I should have logged as admin to perform the same command, but... why did conda downloaded the entire thing before letting me know it would not work? It was such a waste of time and bandwidth...